closed contract. Whose terms constitute the entire agreement between the contracting parties and no clause or provision can be changed or modified without mutual consent. An insurance contract, for example, is a closed contract whereas a construction contract may not be one. See also open contract.
The volt (symbol: V) is the derived unit for electric potential, electric potential difference (voltage), and electromotive force. The volt is named in honour of the Italian physicist Alessandro Volta (1745â1827), who invented the voltaic pile, possibly the first chemical battery.
The voltage is a difference between the electric potentials of two conductors. Hence, to change voltage, only one of the potentials has to change (although both can). In AC power only one of the wires (live/phase) changes it's potential, while the potential of the other one (neutral) remains constant.